Which is why Abraham had a sexual relationship with his sister given that a biblical marriage is simply a personal agreement between two people to shack up together.
The Bible does not record Abraham having any sisters - so how could he have a sexual relationship with one?
Abraham had two brothers - Nahor and Haran - and does not mention him having any sisters.(Genesis 11:27)
I understand that you are referring to either the accounts of Genesis 12 or 20 - when Abraham claims that Sarah is his sister for she is the "daughter of my father, but not the daughter of my mother" (Genesis 20:12) - but that conclusion ignores other relevant facts.
Right after mentioning Abraham's immediate family members Genesis 11:28 claims that Haran - Abraham's brother - "died before his father Terah" - or in other words - Terah (Abraham's father) outlived his son Haran.
Then the very next verse claims that both Abraham and his brother Nahor married women (Sarah and Milcah) and it claims both that Milcah and "Iscah" were Haran's daughters. (Genesis 11:29)
The Talmud and other rabbinic sources claim that "Iscah" is another rendering for "Sarai" - who was later named Sarah - Abraham's wife.
By referencing the Bible, the Talmud and other rabbinic sources it is clear that Sarah was Haran's daughter - making her Abraham's niece.
And the reason that Abraham referred to her as his sister is because Terah - his father - would have adopted her and took care of her upon the death of his son Haran.
Haran most likely did not share the same mother as Abraham and Nahor - so that is why Abraham's mother did not adopt Sarah as Terah had.
This adoption would also explain why Terah married Haran's daughters to his own sons. He was fulfilling his role as the father figure by ensuring they had husbands who could take care of them.
Sarah was
never referred to as Terah's daughter - but she was referred to as his "daughter in law" (Genesis 11:31)
The Biblical record mentioned all three of Terah's sons and also the two daughters and one son of Haran - so why would it not mention that Sarai/Sarah was Terah's daughter?
Because she wasn't.
She was Abraham's "sister" by adoption - not blood.
Why do you believe that "biblical marriage" is simply consensual "shacking up"?
What is your basis for that belief?
Wrong. Romans 1 says nothing at all about female homosexuals since they do not have anal sex, given that Romans 1:26-27 obviously describes anal sex of woman and men which Paul described as "vile" and "unseemly"
Romans 1 does not mention anal sex at all. That would be you applying your own interpretation to the text.
None of that changes the fact that the bible describes Earth as a flat immoveable disc, and describes the universe as a geo-centric dome-shaped tent attached at the circle of the horizon (Matt 4:8 Isaiah 40:22 Eccl 1:5). Nor does it change the fact that the bible does not describe Earth as a rotating globe orbiting the sun. Nor does the bible say that the universe is not geo-centric and is billions of years old.
Ok - so you pick and choose which parts of Isaiah should be interpreted literally and which figuratively or symbolically - depending on how it affects your argument?
You don't detect any logical fallacy there?
Do you also claim that "the Bible" teaches that people are grasshoppers?
If not - why not? It is said in
the very same verse you are referencing about a "disc" and "dome".
Also - why do you believe the Bible should need to describe the Earth orbiting the sun or mention its age in order for it to be a true and accurate record?
Do you believe that
all records need to describe the Earth orbiting the sun or the age of the Earth in order to be considered true and accurate?
If
any record does not mention these things - it is not true and accurate?